Adsorption of butyronitrile at the Hg/aqueous solution interface: Evidence for field dependent solvent-adsorbate surface interaction

Abstract The adsorption of butyronitrilefrom aqueous solutions of not specifically adsorbed electrolytes on a polarized Hg electrode has been studied by means of electrocapillary and capacity measurements. Adsorption has been found to follow a Frumkin isotherm with particle-particle attraction decreasing as the charge becomes more positive than the value of maximum adsorption. Explanation is given in terms of solvent-adsorbate surface interaction being a function of the interfacial electric field. Results are compared with two limiting electrical models for the adsorption layer. The latter is shown to be probably best described by a transition between the two models as the electric field is changed from negative to positive values. Qualitative discussion is also given in terms of Mohilner's surface solution. Conclusions as drawn from the latter are shown not to differ from those obtainable from the experimental results being treated in terms of Frumkin's isotherm.